This invention relates to a locking device for a rectangular connector, and more particularly to a locking device for a rectangular connector miniaturized by shortening it lengthwise in connection with the locking device.
A small type connector for interconnecting light electric appliances consists of a receptacle connector A adapted to be fixed to a case of one appliance as shown in FIG. 1a and a plug connector B adapted to be connected through a cable to another appliance to be connected to the first mentioned appliance as shown in FIG. 1b.
The receptacle connector A comprises an insulating block 1 including a mounting plater 1a and a protrusion 1d. The insulating block 1 is formed with a fitting cavity 1c in which contacts 2 having contact tails 2a are arranged and fixed to inner side surfaces of the cavity 1c. The receptacle connector A further comprises a metal shell 3 surrounding the insulating block 1 and having a metal shell fixing plate 3a for fixing the metal shell 3 to the mounting plate 1a as shown in FIG. 1a. The mounting plate 1a and the metal shell fixing plate 3a are formed with mounting apertures 1b extending therethrough.
The plug connector B comprises a connector body 4 including an insulating block 4a and a fitting protrusion 4b. The fitting protrusion 4b includes contacts 5 having contact tails 5a arranged and fixed onto both side surfaces of the fitting protrusion 4b. The fitting protrusion 4b is adapted to be fitted in the fitting cavity 1c of the receptacle connector A to accomplish an interconnection of the receptacle and plug connectors A and B.
A metal shell 6 is fixed to the insulating block 4a. A connector hood 7 consists of first and second hood members 7a and 7b which are clamped as by means of set screws to hold therein the connector body 4 in a manner extending the metal shell 6 therefrom. Reference numeral 8 denotes a cable.
With such a connector as above described, the plug connector B is in general clamped to the receptacle connector A by means of a locking mechanism in order to prevent disconnection of the connectors A and B due to external tensile forces acting upon the cable 8. In more detail, as shown in FIG. 1b the connector hood 7 is provided therein with locking piece chambers 7d for accommodating locking pieces. Each of the chambers 7d has an opening 7c formed in one side surface of the hood 7. There is provided in each of chambers 7d a locking piece 9 including a pressing portion 9a at one end, a engaging hook-shaped projection 9b and a fulcrum portion 9c at an intermediate position. The locking piece 9 is enclosed in each of the chambers 7d so that the pressing portion 9a extends from the opening 7c and the engaging hook-shaped projection 9b extends toward the metal shell 6.
On the other hand, the metal shell fixing plate 3a of the receptacle connector A is integrally provided on both sides of the metal shell 3 with anchoring plates 10 each having an anchoring recess 10a. When the plug connector B has been inserted in the receptacle connector A, the engaging hook-shaped projections 9b are fitted in the anchoring recesses 10a of the anchoring plates 10.
As can be seen from FIGS. 1a and 1b, the metal shells 3 and 6 are of similar trapezoid in order to ensure only one fitted relation between the receptacle and plug connectors A and B. They are not fitted with each other in a relation in which one of the shells 3 and 6 is turned end for end through 180.degree. relative to the other. In connecting the receptacle and plug connectors A and B, the shell 6 is fitted on the shell 3 to bring the fitting protrusion 4b into the fitting cavity 1c. In this manner, when the contacts 2 and 5 are in contact with each other, the engaging hook-shaped projections 9b are snugly fitted in the anchoring recesses 10a. The plug connector B is thus locked in the receptacle connector A with the aid of the elasticity of the locking pieces 9 as shown in FIG. 2.
On the other hand, in disconnecting the receptacle and plug connectors A and B. The hood 7 is grasped so as to press the pressing portions 9a extending from the openings 7c of the hood 7 so that the engaging hook-shaped projections 9b are removed from the anchoring recesses 10a of the anchoring plates 10 to release the locking action therebetween. The plug connector B can be disconnected from the receptacle connector A under this condition.
With the connector of the prior art, the locking pieces 9 and the anchoring plates 10 constituting the locking mechanism are positioned space apart from the metal shells 3 and 6. Therefore, the receptacle connector A becomes longer in its longitudinal directions by a distance required for providing the anchoring plates 10. Moreover, in the plug connector B, the hood 7 unavoidably becomes wider by a distance required for providing the locking pieces 9. Accordingly, the connector becomes larger against engineer's will.
In recent years, there is a tendency of pitches or intervals of contacts to be narrower so that portions for arranging the contacts become shorter. As a result, the spaces required for providing the anchoring plates 10 become larger relative to distances of the contact arranging portions. Therefore, shortening the longitudinal lengths of connectors has a limitation which would greatly obstruct the miniaturization of appliances by miniaturization of various parts.